1. Field of the Invention
The present invention relates generally to a switching apparatus and method to be used in a communication switching system. It particularly relates to a trunk group switching technique to be used in a satellite communication switching system carrying wide-band signals that uses a code division multiple access (CDMA) scheme and a code division switch on-board the satellite.
2. Background Art
In typical satellite communication systems, the on-board switching equipment primarily comprises a system which acts to receive and then re-transmit user signals to an appropriate destination commonly referred to as a bent-pipe system. The satellite generally acts as a signal relay point to route user signals from a terrestrial origination to a terrestrial destination wherein all pertinent communication switching is performed on the ground. To accomplish actual on-board switching for a plurality of user signals, the complexity of the satellite design quickly multiplies by requiring a digital receiver element for each user signal (call). This hardware requirement greatly increases payload and launch costs, and may limit the number of users that can be supported by a satellite switching platform. The same need to limit equipment cost and size may exist in other communication platforms (e.g., wireless, cellular, land mobile radio, etc).
There is a need to provide a seamless, flexible satellite communication system that can provide desired user services with high performance while keeping satellite design complexity and equipment costs to a minimum.
The present invention provides a method and apparatus for reducing satellite on-board switching complexity to increase overall system performance in a wideband satellite communication system. The present invention overcomes the previously mentioned disadvantages by providing a trunk-coded satellite switching system wherein inbound satellite beams carrying individually encoded user signals that are trunk-coded are advantageously received, processed, and routed to appropriate outbound satellite beams transmitted based on a mapping scheme. The trunk-coded switching allows for a reduction of on-board switching complexity, volume, and costs. One embodiment of the present invention takes advantage of orthogonal coding to perform trunk processing of inbound satellite beams.